Exercise stool



FIG. 1 is a top, front and left side perspective view of an exercise stool, showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a rear elevational view thereof;

FIG. 6 is a bottom, front and right side perspective view thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for an exercise stool, as shown and described. 